The presently disclosed embodiments are directed to the field of manufacturing and molding, and particularly, to injection molding equipment and processes for producing relatively large parts or components.
Large, industrial presses use injection molds, tools or dies that are pressed together under high pressure in one or more operations to receive molding material to thereby form a part or component. Typically, injection molds comprise a set of molds, typically two, that when engaged together, define a hollow interior into which molding material is injected under very high pressure to form parts having a shape or configuration corresponding to the hollow interior defined by the molds.
Injection molds are typically interchangeable, so that different molds can be used in a single press. This enables manufacture of a wide array of different parts from a single press, by merely interchanging the molds in the press. In addition, molds are often replaceable so that after excessive use or if they become damaged, the molds can be replaced with new molds. Moreover, in many pressing operations, after a certain number of cycles, the mold(s) must be cleaned or otherwise serviced. Rather than incurring downtime in the operation, the mold(s) may simply be replaced with other mold(s), so that operation can continue while the previously used mold(s) are serviced.
A consequence of using multiple molds with a single press, is that the molds which are not in use, must be stored yet readily accessible for subsequent use. This is also a consequence of using multiple molds that must be periodically maintained or otherwise serviced.
U.S. Pat. No. 4,805,285 to Reyes is representative of efforts taken in the art to address operations involving the interchangeability and replacement of molds. The '285 patent is directed to a method of changing injection molds. Reyes describes a sequence of operations using an overhead crane and corresponding support tracks extending over the molding press and the region of interest in the facility. The method involves aligning and transporting the molds between the press and areas on the floor around the press at which the molds are stored or otherwise placed.
Although necessary in certain instances, storing molds on the floor is generally undesirable. First, that practice can lead to injury if someone trips or stumbles upon the molds. Second, molds must be maintained to be free of dirt or other particles. This is particularly so for molds used in producing high precision or high tolerance parts. Placing molds on the floor can lead to contamination of the molds. Third, molds frequently contain coatings or residual amounts of liquids such as oils, water, and various chemical agents used in the molding process. Storing such molds on the floor can promote collection of these liquids and agent(s) on the floor and into the work environment, which may create safety hazards and violate local safety codes. Fourth, storing molds on the floor uses valuable floor space. This may be particularly undesirable in many industrial and manufacturing facilities.
Another reason for not simply placing unused molds on the floor, pertains to desirability in tracking and identifying the location of all molds associated with a particular press, or perhaps those used in a facility or region of a facility. In highly automated manufacturing processes using one or more presses, the various molds associated with the press(es) are stored and their location tracked by electronic control systems such that prior to a mold change operation, the location and the state of the successor mold is known by the system. This increases overall efficiency of the process as downtime resulting from searching for the desired mold is avoided. Artisans have further developed strategies for reducing downtime otherwise resulting from mold changing operations. These strategies are typically referred to as “Quick Mold Change” (QMC) or “Quick Die Change” (QDC) techniques.
In view of these and other factors, mold carts have been developed and are typically used in conjunction with presses to transport molds away from the floor regions around the press and more recently, to facilitate storage and stocking of molds. Mold carts can be used to transport one or more molds between presses and various regions in the manufacturing facility. Mold carts can also serve to store one or more molds, such as by receiving and supporting the mold and then transporting the mold(s) to a designated storage region in the facility. Mold carts may also be equipped with a mold receiving surface having a selectively adjustable position and orientation. This enables the receiving surface to be positioned alongside the press to readily receive the mold from the press or place a new or successor mold in a proper position for placement in the press.
In view of the foregoing, many different types of mold carts are commercially available. Mold carts are available with remote controls for “driving” the cart and controlling its operations. Mold carts that can be interfaced with automated processes are also known.
As process operations have grown in complexity and increased in efficiency, mold carts have also been used to support just-in-time and/or just-in-sequence manufacturing strategies. And so, a new generation of automatic carts has been developed which can be interfaced with a plant-wide control system to selectively store, transport, pre-stage, and post-stage molds at desired locations and times in a manufacturing system.
Although mold carts provide numerous features and benefits, they are not always used. The cost of such carts may be prohibitive for some businesses. The layout or physical configuration of certain operations may also be a barrier to their use. Moreover, for relatively large molds, such as those used to produce large parts or components, the significant size and mass of the molds typically precludes the use of mold carts.
In response to applications in which mold carts are not used, artisans have devised assemblies and strategies directed to achieving one or more of the previously noted benefits that mold carts typically satisfy. One such strategy is to incorporate storage regions directly in or on the press. An example of such a press is described in U.S. Pat. No. 6,699,026 to Maru et al. Maru et al. describe an injection molding apparatus having a tiered frame. The tiered frame is provided with upper and lower storage sections which are said to retain one or more “injection molding machine units.” Although satisfactory for small-scale applications, the tiered frame is insufficient for supporting the massive molds typically used in injection molding large parts or components.
U.S. Pat. No. 7,134,860 to Pierik et al. describes a stationary mold access and storage structure that is positioned over a press or other machine. The structure provides an elevated mold receiving surface with designated regions for mold placement and storage. Although providing a space-saving function, it is doubtful that the structure could support massive and heavy molds typically used in injection molding of large parts.
In addition, neither of the structures described in the '026 patent to Maru et al. nor the '860 patent to Pierik et al. provide any means for moving the molds from the press to a location remote from the press, and vice versa. And so, neither of the structures described in the noted patents provide any solution or assistance in changing or replacing the molds.
Assemblies are known which serve to change molds, or assist in such operations. U.S. Pat. No. 4,529,371 to Nickley describes a mold changer for an injection molding machine. The machine uses mold carriages that can be horizontally positioned alongside the molding machine. The carriages can receive and support a mold as it is removed from or transferred to the machine. In addition, U.S. Pat. No. 6,032,491 to Nitschke et al. describes an assembly for mold changing in a heated glass sheet forming station. The assembly uses a rail mounted unloading cart that transports the heated molds between various stations.
Although the '371 patent to Nickley and the '491 patent to Nitschke et al. provide similar mechanisms and strategies for mold changing, each approach still requires an assembly that consumes significant amounts of floor space around the press. Furthermore, it is questionable whether such mechanisms could be used in conjunction with massive molds employed in the production of large injection molded parts.
Although satisfactory in many respects, a need remains for an assembly and strategy for receiving, moving, and supporting one or more molds, and for the assembly when not in use, to not consume valuable floor space around the press.